Monomer Emulsified Aqueous Ring-Opening Metathesis Polymerization (ME-ROMP) for the Synthesis of Water-Soluble Molecular Bottlebrushes with a Precise Structure

Abstract

Water-soluble molecular bottlebrushes (MBBs) with various functions and tunable morphologies have found promising application prospects in the biorelevant field. However, the facile synthesis of water-soluble MBBs with well-defined architectures is challenging by different chemistry. Herein, we explore the versatility of monomer emulsified aqueous ring-opening metathesis polymerization (ME-ROMP) for the facile synthesis of water-soluble MBBs via a grafting-through strategy. The grafting-through ME-ROMP was carried out by injecting a tiny amount of Grubbs’ third-generation catalyst (G3) solution of CH2Cl2 into the aqueous solution of norbornene macromonomers (NB MMs) without deoxygenation, forming NB MMs-stabilized CH2Cl2/H2O emulsions. In this ME-ROMP, the NB moieties and G3 are concentrated in CH2Cl2 droplets so that catalyst decomposition could be significantly suppressed and the steric hindrance of MMs reduced, leading to an accelerated polymerization. The results demonstrate that the ME-ROMP of NB MMs is living with ultrafast polymerization rates and near quantitative initiation and monomer conversion, producing well-defined water-soluble MBBs with diverse compositions and tunable contour lengths.